[PATCH u-boot v2019.04-aspeed-openbmc v2] aspeed: add CONFIG_ASPEED_ENABLE_BACKDOORS

Zev Weiss zev at bewilderbeest.net
Fri Apr 15 08:40:04 AEST 2022


On ast2400 and ast2500 we now default to disabling the various hardware
backdoor interfaces as is done on ast2600, though the Kconfig option can
be set to y to re-enable them if desired for debugging.

This patch is based on a patch by Andrew Jeffery for an older u-boot
branch in the OpenBMC tree for the df-isolate-bmc distro feature flag.

Signed-off-by: Zev Weiss <zev at bewilderbeest.net>
---

I've tested this on both ast2500 and ast2400, with the slight caveat
that the only ast2400 hardware I have is a hostless (BMC-only) system.

Changes since v1 [0]:
 - extended to cover ast2400
 - inverted sense of Kconfig option, default (n) is now secure mode
 - renamed some register/bit macros more appropriately

[0] https://lore.kernel.org/openbmc/20220414040448.27100-1-zev@bewilderbeest.net/

 arch/arm/include/asm/arch-aspeed/platform.h   |  7 ++
 .../arm/include/asm/arch-aspeed/scu_ast2400.h |  7 ++
 .../arm/include/asm/arch-aspeed/scu_ast2500.h |  8 ++
 arch/arm/mach-aspeed/Kconfig                  | 13 ++++
 arch/arm/mach-aspeed/ast2400/board_common.c   | 68 +++++++++++++++++
 arch/arm/mach-aspeed/ast2500/board_common.c   | 73 +++++++++++++++++++
 6 files changed, 176 insertions(+)

diff --git a/arch/arm/include/asm/arch-aspeed/platform.h b/arch/arm/include/asm/arch-aspeed/platform.h
index f016bdaba3e7..f05747642f38 100644
--- a/arch/arm/include/asm/arch-aspeed/platform.h
+++ b/arch/arm/include/asm/arch-aspeed/platform.h
@@ -15,24 +15,31 @@
 /*********************************************************************************/
 #if defined(CONFIG_ASPEED_AST2400)
 #define ASPEED_MAC_COUNT	2
+#define ASPEED_SDRAM_CTRL	0x1e6e0000
 #define ASPEED_HW_STRAP1	0x1e6e2070
 #define ASPEED_REVISION_ID	0x1e6e207C
 #define ASPEED_SYS_RESET_CTRL	0x1e6e203C
 #define ASPEED_VGA_HANDSHAKE0	0x1e6e2040	/*	VGA fuction handshake register */
+#define ASPEED_PCIE_CONFIG_SET	0x1e6e2180
 #define ASPEED_DRAM_BASE	0x40000000
 #define ASPEED_SRAM_BASE	0x1E720000
+#define ASPEED_LPC_CTRL		0x1e789000
 #define ASPEED_SRAM_SIZE	0x8000
 #define ASPEED_FMC_CS0_BASE	0x20000000
 #elif defined(CONFIG_ASPEED_AST2500)
 #define ASPEED_MAC_COUNT	2
+#define ASPEED_SDRAM_CTRL	0x1e6e0000
+#define ASPEED_MISC1_CTRL	0x1e6e202C
 #define ASPEED_HW_STRAP1	0x1e6e2070
 #define ASPEED_HW_STRAP2	0x1e6e20D0
 #define ASPEED_REVISION_ID	0x1e6e207C
 #define ASPEED_SYS_RESET_CTRL	0x1e6e203C
 #define ASPEED_VGA_HANDSHAKE0	0x1e6e2040	/*	VGA fuction handshake register */
+#define ASPEED_PCIE_CONFIG_SET	0x1e6e2180
 #define ASPEED_MAC_COUNT	2
 #define ASPEED_DRAM_BASE	0x80000000
 #define ASPEED_SRAM_BASE	0x1E720000
+#define ASPEED_LPC_CTRL		0x1e789000
 #define ASPEED_SRAM_SIZE	0x9000
 #define ASPEED_FMC_CS0_BASE	0x20000000
 #elif defined(CONFIG_ASPEED_AST2600)
diff --git a/arch/arm/include/asm/arch-aspeed/scu_ast2400.h b/arch/arm/include/asm/arch-aspeed/scu_ast2400.h
index 9c5d96ae84b9..55875fd8312f 100644
--- a/arch/arm/include/asm/arch-aspeed/scu_ast2400.h
+++ b/arch/arm/include/asm/arch-aspeed/scu_ast2400.h
@@ -8,6 +8,7 @@
 #define SCU_HWSTRAP_VGAMEM_MASK		(3 << SCU_HWSTRAP_VGAMEM_SHIFT)
 #define SCU_HWSTRAP_MAC1_RGMII		(1 << 6)
 #define SCU_HWSTRAP_MAC2_RGMII		(1 << 7)
+#define SCU_HWSTRAP_LPC_SIO_DEC_DIS	(1 << 20)
 #define SCU_HWSTRAP_DDR4		(1 << 24)
 #define SCU_HWSTRAP_CLKIN_25MHZ		(1 << 23)
 
@@ -104,6 +105,12 @@
 #define SCU_CLKDUTY_RGMII2TXCK_SHIFT	16
 #define SCU_CLKDUTY_RGMII2TXCK_MASK	(0x7f << SCU_CLKDUTY_RGMII2TXCK_SHIFT)
 
+#define SCU_PCIE_CONFIG_SET_VGA_MMIO	(1 << 1)
+#define SCU_PCIE_CONFIG_SET_BMC_EN	(1 << 8)
+#define SCU_PCIE_CONFIG_SET_BMC_MMIO	(1 << 9)
+#define SCU_PCIE_CONFIG_SET_BMC_DMA	(1 << 14)
+
+
 struct ast2400_clk_priv {
 	struct ast2400_scu *scu;
 };
diff --git a/arch/arm/include/asm/arch-aspeed/scu_ast2500.h b/arch/arm/include/asm/arch-aspeed/scu_ast2500.h
index 8fe4028e4ff0..06dc998afaa8 100644
--- a/arch/arm/include/asm/arch-aspeed/scu_ast2500.h
+++ b/arch/arm/include/asm/arch-aspeed/scu_ast2500.h
@@ -11,6 +11,7 @@
 #define SCU_HWSTRAP_VGAMEM_MASK		(3 << SCU_HWSTRAP_VGAMEM_SHIFT)
 #define SCU_HWSTRAP_MAC1_RGMII		(1 << 6)
 #define SCU_HWSTRAP_MAC2_RGMII		(1 << 7)
+#define SCU_HWSTRAP_LPC_SIO_DEC_DIS	(1 << 20)
 #define SCU_HWSTRAP_DDR4		(1 << 24)
 #define SCU_HWSTRAP_CLKIN_25MHZ		(1 << 23)
 
@@ -107,6 +108,13 @@
 #define SCU_CLKDUTY_RGMII2TXCK_SHIFT	16
 #define SCU_CLKDUTY_RGMII2TXCK_MASK	(0x7f << SCU_CLKDUTY_RGMII2TXCK_SHIFT)
 
+#define SCU_PCIE_CONFIG_SET_VGA_MMIO	(1 << 1)
+#define SCU_PCIE_CONFIG_SET_BMC_EN	(1 << 8)
+#define SCU_PCIE_CONFIG_SET_BMC_MMIO	(1 << 9)
+#define SCU_PCIE_CONFIG_SET_BMC_DMA	(1 << 14)
+
+#define SCU_MISC_DEBUG_UART_DISABLE	(1 << 10)
+
 struct ast2500_clk_priv {
 	struct ast2500_scu *scu;
 };
diff --git a/arch/arm/mach-aspeed/Kconfig b/arch/arm/mach-aspeed/Kconfig
index 579a547df61e..4bbf6fff326d 100644
--- a/arch/arm/mach-aspeed/Kconfig
+++ b/arch/arm/mach-aspeed/Kconfig
@@ -45,6 +45,19 @@ config ASPEED_AST2600
 	  which is enabled by support of LPC and eSPI peripherals.
 endchoice
 
+config ASPEED_ENABLE_BACKDOORS
+	bool "Enable hardware features that provide back-door access to the BMC"
+	depends on ASPEED_AST2400 || ASPEED_AST2500
+	help
+	  Aspeed BMCs include a number of hardware features that
+	  provide access to BMC internals that is undesirable in
+	  production systems for security reasons (iLPC2AHB, P2A,
+	  PCIe, debug UART, X-DMA, LPC2AHB), but may be useful for
+	  debugging.  Say Y here to enable these features for a debug
+	  (insecure) build.  (This option is not available for the
+	  ast2600, on which the backdoors are disabled
+	  unconditionally.)
+
 config ASPEED_PALLADIUM
 	bool "Aspeed palladium for simulation"
 	default n
diff --git a/arch/arm/mach-aspeed/ast2400/board_common.c b/arch/arm/mach-aspeed/ast2400/board_common.c
index 3829b069342e..10ce7af8c108 100644
--- a/arch/arm/mach-aspeed/ast2400/board_common.c
+++ b/arch/arm/mach-aspeed/ast2400/board_common.c
@@ -4,14 +4,82 @@
 #include <ram.h>
 #include <timer.h>
 #include <asm/io.h>
+#include <asm/arch/platform.h>
+#include <asm/arch/scu_ast2400.h>
 #include <asm/arch/timer.h>
 #include <linux/err.h>
 #include <dm/uclass.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#if !defined(CONFIG_ASPEED_ENABLE_BACKDOORS)
+#define AST_LPC_HICR5 0x080
+# define LPC_HICR5_ENFWH BIT(10)
+#define AST_LPC_HICRB 0x100
+# define LPC_HICRB_SIO_ILPC2AHB_DIS BIT(6)
+
+#define AST_SDMC_PROTECT 0x00
+# define SDRAM_UNLOCK_KEY 0xfc600309
+#define AST_SDMC_GFX_PROT 0x08
+# define SDMC_GFX_PROT_VGA_CURSOR BIT(0)
+# define SDMC_GFX_PROT_VGA_CG_READ BIT(1)
+# define SDMC_GFX_PROT_VGA_ASCII_READ BIT(2)
+# define SDMC_GFX_PROT_VGA_CRT BIT(3)
+# define SDMC_GFX_PROT_PCIE BIT(16)
+# define SDMC_GFX_PROT_XDMA BIT(17)
+
+static void isolate_bmc(void)
+{
+	bool sdmc_unlocked;
+	u32 val;
+
+	/* iLPC2AHB */
+	val = readl(ASPEED_HW_STRAP1);
+	val |= SCU_HWSTRAP_LPC_SIO_DEC_DIS;
+	writel(val, ASPEED_HW_STRAP1);
+
+	val = readl(ASPEED_LPC_CTRL + AST_LPC_HICRB);
+	val |= LPC_HICRB_SIO_ILPC2AHB_DIS;
+	writel(val, ASPEED_LPC_CTRL + AST_LPC_HICRB);
+
+	/* P2A, PCIe BMC */
+	val = readl(ASPEED_PCIE_CONFIG_SET);
+	val &= ~(SCU_PCIE_CONFIG_SET_BMC_DMA
+	         | SCU_PCIE_CONFIG_SET_BMC_MMIO
+	         | SCU_PCIE_CONFIG_SET_BMC_EN
+	         | SCU_PCIE_CONFIG_SET_VGA_MMIO);
+	writel(val, ASPEED_PCIE_CONFIG_SET);
+
+	/* X-DMA */
+	sdmc_unlocked = readl(ASPEED_SDRAM_CTRL + AST_SDMC_PROTECT);
+	if (!sdmc_unlocked)
+		writel(SDRAM_UNLOCK_KEY, ASPEED_SDRAM_CTRL + AST_SDMC_PROTECT);
+
+	val = readl(ASPEED_SDRAM_CTRL + AST_SDMC_GFX_PROT);
+	val |= (SDMC_GFX_PROT_VGA_CURSOR
+	        | SDMC_GFX_PROT_VGA_CG_READ
+	        | SDMC_GFX_PROT_VGA_ASCII_READ
+	        | SDMC_GFX_PROT_VGA_CRT
+	        | SDMC_GFX_PROT_PCIE
+	        | SDMC_GFX_PROT_XDMA);
+	writel(val, ASPEED_SDRAM_CTRL + AST_SDMC_GFX_PROT);
+
+	if (!sdmc_unlocked)
+		writel(~SDRAM_UNLOCK_KEY, ASPEED_SDRAM_CTRL + AST_SDMC_PROTECT);
+
+	/* LPC2AHB */
+	val = readl(ASPEED_LPC_CTRL + AST_LPC_HICR5);
+	val &= ~LPC_HICR5_ENFWH;
+	writel(val, ASPEED_LPC_CTRL + AST_LPC_HICR5);
+}
+#endif
+
 __weak int board_init(void)
 {
+#if !defined(CONFIG_ASPEED_ENABLE_BACKDOORS)
+	isolate_bmc();
+#endif
+
 	gd->bd->bi_boot_params = CONFIG_SYS_SDRAM_BASE + 0x100;
 
 	return 0;
diff --git a/arch/arm/mach-aspeed/ast2500/board_common.c b/arch/arm/mach-aspeed/ast2500/board_common.c
index ce541e88fb8e..29554011eb38 100644
--- a/arch/arm/mach-aspeed/ast2500/board_common.c
+++ b/arch/arm/mach-aspeed/ast2500/board_common.c
@@ -7,18 +7,91 @@
 #include <ram.h>
 #include <timer.h>
 #include <asm/io.h>
+#include <asm/arch/platform.h>
+#include <asm/arch/scu_ast2500.h>
+#include <asm/arch/sdram_ast2500.h>
 #include <asm/arch/timer.h>
 #include <linux/err.h>
 #include <dm/uclass.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#if !defined(CONFIG_ASPEED_ENABLE_BACKDOORS)
+#define AST_LPC_HICR5 0x080
+# define LPC_HICR5_ENFWH BIT(10)
+#define AST_LPC_HICRB 0x100
+# define LPC_HICRB_SIO_ILPC2AHB_DIS BIT(6)
+
+# define AST_SDMC_PROTECT 0x00
+# define AST_SDMC_GFX_PROT 0x08
+#  define SDMC_GFX_PROT_VGA_CURSOR BIT(0)
+#  define SDMC_GFX_PROT_VGA_CG_READ BIT(1)
+#  define SDMC_GFX_PROT_VGA_ASCII_READ BIT(2)
+#  define SDMC_GFX_PROT_VGA_CRT BIT(3)
+#  define SDMC_GFX_PROT_PCIE BIT(16)
+#  define SDMC_GFX_PROT_XDMA BIT(17)
+
+static void isolate_bmc(void)
+{
+	bool sdmc_unlocked;
+	u32 val;
+
+	/* iLPC2AHB */
+	val = readl(ASPEED_HW_STRAP1);
+	val |= SCU_HWSTRAP_LPC_SIO_DEC_DIS;
+	writel(val, ASPEED_HW_STRAP1);
+
+	val = readl(ASPEED_LPC_CTRL + AST_LPC_HICRB);
+	val |= LPC_HICRB_SIO_ILPC2AHB_DIS;
+	writel(val, ASPEED_LPC_CTRL + AST_LPC_HICRB);
+
+	/* P2A, PCIe BMC */
+	val = readl(ASPEED_PCIE_CONFIG_SET);
+	val &= ~(SCU_PCIE_CONFIG_SET_BMC_DMA
+	         | SCU_PCIE_CONFIG_SET_BMC_MMIO
+	         | SCU_PCIE_CONFIG_SET_BMC_EN
+	         | SCU_PCIE_CONFIG_SET_VGA_MMIO);
+	writel(val, ASPEED_PCIE_CONFIG_SET);
+
+	/* Debug UART */
+	val = readl(ASPEED_MISC1_CTRL);
+	val |= SCU_MISC_DEBUG_UART_DISABLE;
+	writel(val, ASPEED_MISC1_CTRL);
+
+	/* X-DMA */
+	sdmc_unlocked = readl(ASPEED_SDRAM_CTRL + AST_SDMC_PROTECT);
+	if (!sdmc_unlocked)
+		writel(SDRAM_UNLOCK_KEY, ASPEED_SDRAM_CTRL + AST_SDMC_PROTECT);
+
+	val = readl(ASPEED_SDRAM_CTRL + AST_SDMC_GFX_PROT);
+	val |= (SDMC_GFX_PROT_VGA_CURSOR
+	        | SDMC_GFX_PROT_VGA_CG_READ
+	        | SDMC_GFX_PROT_VGA_ASCII_READ
+	        | SDMC_GFX_PROT_VGA_CRT
+	        | SDMC_GFX_PROT_PCIE
+	        | SDMC_GFX_PROT_XDMA);
+	writel(val, ASPEED_SDRAM_CTRL + AST_SDMC_GFX_PROT);
+
+	if (!sdmc_unlocked)
+		writel(~SDRAM_UNLOCK_KEY, ASPEED_SDRAM_CTRL + AST_SDMC_PROTECT);
+
+	/* LPC2AHB */
+	val = readl(ASPEED_LPC_CTRL + AST_LPC_HICR5);
+	val &= ~LPC_HICR5_ENFWH;
+	writel(val, ASPEED_LPC_CTRL + AST_LPC_HICR5);
+}
+#endif
+
 __weak int board_init(void)
 {
 	struct udevice *dev;
 	int i;
 	int ret;
 
+#if !defined(CONFIG_ASPEED_ENABLE_BACKDOORS)
+	isolate_bmc();
+#endif
+
 	gd->bd->bi_boot_params = CONFIG_SYS_SDRAM_BASE + 0x100;
 
 	/*
-- 
2.35.1



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